1. Field of the Invention
The present invention relates to a conveyor device for conveying, for example, powder, liquid, or gas stored in a flexible container to other devices, and to an image forming apparatus that uses the conveyor device as a toner-conveying device.
2. Description of the Related Art
This type of conveyor device is used in various technical fields. For example, conveyor devices disclosed in Japanese Unexamined Patent Application Publication Nos. 2001-194907, 2001-324863, and 2002-72649 are used in the field of an image forming apparatus. These conveyor devices are used as toner-conveying devices that supply toner from a toner container to a developing device. The toner container mounted in the toner-conveying devices is made of a bag-shaped flexible material, and can be contracted and reduced in volume by a suction force of a suction pump. The shape and size of a hard toner container, such as a cartridge or a bottle, does not change with use. In contrast, the volume of the toner container disclosed in the above publications decreases with use. Therefore, this toner container is easier for the user to handle after use than the hard bottle container. Moreover, it is possible to reduce the cost of transporting the toner container from the user to a manufacturer to replace the used toner container by a new one for reclaiming.
In such a flexible toner container, a cap made of, for example, plastic is generally mounted at an opening provided in a flexible bag. To supply toner to the developing device, the toner container is loaded in the toner-conveying device, and the cap of the toner container is then engaged with a nozzle (conveying-path forming member) of the toner-conveying device. The interior of the toner container thereby communicates with the conveying path in the toner-conveying device. Toner stored in the toner container is conveyed to the developing device through the conveying path by a suction force of the suction pump.
When the flexible toner container is loaded in the toner-conveying device, the cap must be properly placed in a predetermined position (setting position) in the toner-conveying device to be coupled to the nozzle in a normal manner. However, the cap frequently collides with or is pushed by other things during distribution and handling before loading. Since the bag of the toner container is flexible, the posture of the cap is interfered with by such a collision or pushing.
FIG. 13 is a side view showing an example of a toner container in which a cap is in an incorrect posture. A bag of the toner container has folds on its side faces (front and rear sides of the plane of the figure) to take a predetermined shape after volume reduction. However, folds are not provided on front and rear faces (left and right sides of the plane of the figure) of the bag. For this reason, the front and rear faces of the bag have a flexural rigidity lower than that of the side faces. Therefore, the cap tends to tilt toward the front or rear face of the bag and interferes with its posture, as shown in FIG. 13. In particular, since a portion of the bag near the cap is tapered so that inner toner easily concentrates at the cap during a toner supply operation, the posture of the cap is prone to be interfered with.
When the toner container having the cap in an incorrect posture is loaded in the toner-conveying device, the cap is not placed in a predetermined position inside the toner-conveying device. Therefore, the nozzle of the toner-conveying device is not properly coupled to the cap, and a normal toner supply operation cannot be performed. Although the operator can correct the posture of the cap before loading, this is troublesome for the operator, and convenience for the operator is substantially reduced.
Even when the cap is in a correct posture before loading, if the cap collides with something while the toner container is being loaded in the toner-conveying device, the posture of the cap is easily interfered with because the bag of the toner container is flexible. Therefore, the operator also must take care so that the posture of the cap will not be interfered with during loading of the toner container, and this reduces convenience.
While the operator generally loads the toner container while holding the bag, it is difficult for the operator to correct the posture of the cap by handling the held portion. Since the bag is flexible, a force applied to the held portion by the operator is not easily transmitted to the cap, and it is difficult for the operator holding the bag to control the position and posture of the cap.
To properly place the cap in a predetermined position without reducing the convenience for the operator, two methods for preventing interference with the posture of the cap can be adopted.
More specifically, a first method is to increase the thickness of the bag for higher rigidity. In this method, however, since a sheet material that forms the bag is thick, heat is not easily transmitted to the inner side of the sheet material during a seam-welding process for welding a seam of the sheet. For this reason, welding failure may occur, or the strength may decrease. To prevent welding failure or a decrease in strength, time taken for the seam-welding process must be increased, and the manufacturing cost of the bag increases. When the posture of the cap is interfered with by an external force for some reason, creases are made and clearly remain after the posture is corrected. Consequently, the bag does not take a desired shape after volume reduction, but deforms into an undesirable shape along the creases.
A second method is to reduce the rigidity of the bag so that the posture of the cap is easily corrected. In this method, however, the thickness of the sheet material of the bag is reduced, and a portion of the bag near the cap is first crushed at the early stage of the volume reduction process. When the portion is crushed, discharging of toner from the toner container is hindered, the amount of toner to be discharged varies, and much toner remains in the toner container. Furthermore, since the operator generally holds the bag, as described, when the bag is too soft, ease of handling and convenience are reduced.
From the above viewpoints, there is a practically desirable range of rigidity of the bag in the toner container, and it is difficult to overcome the above problems in the range by preventing the posture of the cap from being interfered with.
The above problems occur not only to the mechanism for supplying toner from the toner container to the developing device, but also to a mechanism for conveying a material stored in a container made of a flexible material to other devices.